1. Field of the Invention
The present invention relates to a scanning device for scanning a scale graduation for detecting relative movements of the scanning device with respect to the scale graduation, having a plurality of sensor fields, wherein a primary sensor field is used for detecting relative movements along a first spatial direction, and a secondary sensor field for detecting relative movements along a second spatial direction, which is linearly independent of the first one. The present invention further relates to a position measuring system utilizing the scanning device.
2. Discussion of Related Art
Such a scanning device is used for detecting relative movements of the scanning device with respect to a scale graduation, and for this purpose has a plurality of sensor fields (i.e. sensor modules, each including several sensors), a primary sensor field of which is used for detecting relative movements along a first (linear) spatial direction, a secondary sensor field for detecting relative movements along a second spatial direction, which is linearly independent of the first spatial direction and, if desired (optionally), a tertiary sensor field for detecting rotary movements of the scanning device with respect to the scale graduation, in particular to rotary movements around an axis extending perpendicularly to the plane defined by the first spatial direction and the second spatial direction, so that the rotary movement extends in this plane.
Such a scanning device is known from DE 100 54 376 A1 and is used as a component of a position measuring system for detecting the relative positions of two objects which are movable with respect to each other, for example two machine elements in the form of a stator and a rotor, of which the one group of components is connected with the scanning device, and the other group of components with the scale graduation.